Square Kilometers to Square Miles Converter
Type an area in square kilometers and the equivalent in square miles shows up immediately. Read on for the factor, why it is not simply 0.6214, worked examples and a table of common sizes.
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Created by the Reeliy Editorial Team. Last updated: Oct 19, 2026
How many square miles are in a square kilometer?
One square kilometer equals about 0.3861021585 square miles. It is the reciprocal of 2.589988110336, the number of square kilometers in a square mile.
sq mi = km2 ÷ 2.589988110336
The same thing can be written as a multiplication: sq mi = km2 × 0.3861021585. The converter shows eight decimal places, so 1 km2 appears as 0.38610216.
Why the factor is not 0.6214
A kilometer is about 0.621371 miles, and that number is the right one for distances. An area is a length multiplied by a length, so the conversion factor is multiplied by itself as well: 0.621371 × 0.621371 ≈ 0.386102. Using 0.6214 on an area would overstate the result by about 61%.
A handy way to remember it: a square kilometer is a bit more than a third of a square mile, or roughly 39% of one.
How to convert square kilometers to square miles
- Enter the area in square kilometers in the first box.
- Read the area in square miles from the second box.
- To estimate by hand, multiply by 0.386 or take 39% of the number.
Example 1: a reserve of 250 km2 is 250 ÷ 2.589988110336 = 96.5255 sq mi.
Example 2: a region of 1,200 km2 is 463.3226 sq mi, and a lake of 78 km2 is 30.116 sq mi.
Check your work: convert the answer back by multiplying by 2.589988. For the reserve, 96.5255 × 2.589988 gives 250.0 km2 again, which confirms the direction of the factor.
The converter rounds to eight decimal places and drops trailing zeros. A very small input, such as 0.000001 km2, therefore shows as 3.9e-7, which is exponent notation for 0.00000039.
Square kilometers to square miles table
| Square kilometers | Square miles |
|---|---|
| 1 | 0.3861 |
| 2 | 0.7722 |
| 5 | 1.9305 |
| 10 | 3.861 |
| 25 | 9.6526 |
| 50 | 19.3051 |
| 100 | 38.6102 |
| 250 | 96.5255 |
| 500 | 193.0511 |
| 1,000 | 386.1022 |
Where you meet these units
Geography books, national statistics offices and most atlases state the size of countries, islands, lakes and parks in square kilometers. American and some British sources use square miles instead, so comparing a figure from one with a figure from the other needs this conversion.
For the reverse direction use the square miles to square kilometers converter, or browse the whole area converter for hectares, acres and more.
Frequently asked questions
How many square miles are in a square kilometer?
About 0.3861 square miles, or exactly 1 ÷ 2.589988110336.
How do I convert 100 square kilometers to square miles?
Divide by 2.589988110336, or multiply by 0.3861. The answer is 38.6102 square miles.
Is a square kilometer bigger than a square mile?
No. A square mile is about 2.59 times as large as a square kilometer.
How many square meters are in a square kilometer?
One square kilometer is 1,000,000 square meters.
References
- Thompson, A. and Taylor, B. N. (2008). Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 edition.
- International yard and pound agreement of 1959, which fixed the international yard at exactly 0.9144 meter.
Cite this converter and page
If you use this page in your work, you can cite it as:
Reeliy Editorial Team. (2026). Square Kilometers to Square Miles Converter. Reeliy. https://reeliy.com/converters/convert-square-kilometers-to-sq-miles“Square Kilometers to Square Miles Converter.” Reeliy, 2026, https://reeliy.com/converters/convert-square-kilometers-to-sq-miles.